Prior art valves for controlling or regulating fluids are known, which include a valve body and a linear valve drive formed separately from the valve body. The linear valve drive and the valve body are connected to one another in order to form the valve.
The linear valve drive has a drive unit, e.g. a piezoelectric actuator. The drive unit can displace a valve closure element by means of an actuating device, which is provided in the linear valve drive, or an actuating mechanism. For instance, the linear valve drive can move the valve closure element at least to an open and/or a closed position in which the valve closure element lies on a valve seat formed in the valve body and seals said valve seat so that no fluid can flow through the valve.
Furthermore, it is known from the prior art that an adjusting device or an adjusting option can be provided, by means of which a change in length in the linear valve drive can be compensated for, in particular the actuating device. The change in length is brought about by temperature changes or service life effects, e.g. setting effects.
A specific material pairing can be used in the actuating device, which can compensate for changes in length induced at least by temperature. However, it is not thereby possible to compensate for any service life effects which occur.
According to one further possibility, a voltage is applied if the drive unit is a piezoelectric actuator. As a result, a change in length in the linear valve drive is actively produced, in particular a change in length of the piezoelectric actuator, so that in terms of valve control technology, said actuator has a changed length in the initial state. The actively adjusted change in length compensates for the changes in length produced by temperature changes or service life effects.
A further possibility which is known from the prior art is to provide clearance or an idle stroke which can be utilized in order to react to any occurring changes in length of the actuating device and to compensate for same. An idle (no-load) stroke is the particular displacement path of the actuating device or the actuating mechanism in the linear valve drive which is not converted into an axial movement of the valve closure element because initially the clearance present in the actuating device or the actuating mechanism must be overcome.
DE 10 2010 027 518 A1 discloses e.g. an NC valve, i.e. a normally closed valve, which has an adjustable idle stroke which can be adjusted by means of an externally arranged tensioning element. The force originating from the actuator is transmitted to the valve closure element via a mechanism provided in the linear valve drive, wherein the actuating mechanism comprises inter alia lever devices, i.e. deflecting mechanisms.
JP-H11-173 440 A describes a valve arrangement in which a clearance in the form of a gap which occurs during assembly of the valve arrangement is to be compensated for once so that it is no longer present. This is necessary in that case to ensure that a piezo stack which is provided in the valve arrangement remains under the required pre-loading, in that the piezo stack lies via a collar against a union nut directly, i.e. without any clearance.